Abstract 1777: Increases in Folic Acid Intake in the Preconceptual Period Reduce Birth Prevalence of Severe Congenital Heart Disease
Introduction. Preconceptual intake of folic acid reduces the risk of neural tube defects; animal studies suggest a similar protective effect for congenital heart disease (CHD). Guidelines to recommend folic acid supplements were released in Canada in 1993, while flour fortification was recommended in 1996 and became mandatory in 1998. We measured temporal changes in the birth prevalence of severe CHD in the 4 periods marked by these public health measures: pre-supplementation, pre-fortification, transition to fortification and post-fortification.
Methods. We conducted a time trend analysis using administrative data from Quebec, Canada. The study population consisted of live births from 1990 to 2001 diagnosed with severe CHD and identified using ICD9 diagnoses for Tetralogy of Fallot, endocardial cushion defect, univentricular hearts, truncus arteriosus or transposition complexes coded by a cardiovascular specialist. Birth prevalence was measured quarterly as live births with CHD per 1,000 live births in Quebec population. We used linear regression to estimate observed and expected average changes in birth prevalence in different periods.
Results. We identified 2,238 live births with severe CHD. Relative to the pre-supplementation period, the average birth prevalence did not decrease significantly until the post-fortification period (1.94 vs. 1.72/1,000 live births, p =0.04). Quarterly trends are presented in the figure⇓.
Conclusion. Public health measures to increase folic acid intake were followed by a decrease in birth prevalence of severe CHD, supporting the hypothesis that folic acid may have had a preventive effect on CHD.